strange error during runtime of custom JCA adapter

Hi all,

we're about developing an JCA adapter for XI. Therefore, we originally derrived SAP's sample adapter. During startup, the adapter's main class (SPIManagedConnectionFactory) is starting a thread for outbound processing, which perodically checks for unsent messages in the database via a SessionBean.

Everything is working fine, but after (I guess) two days, the instantiation of the SessionBean starts to fail and with this, the thread doesn't work any more. After a restart of the adapter, everything's fine again.

The call of the SessionBean is done via it's local interfaces.

Here's the exception's stack trace:

com.sap.engine.services.ejb.exceptions.BaseEJBException: Exception in method getUnsentMessages.
	at xi.adapter.messageDB.MessageServiceLocalLocalObjectImpl40.getUnsentMessagesWithSendTimeReached(MessageServiceLocalLocalObjectImpl40.java:1155)
	at xi.adapter.outbound.AdapterOutboundProcessor.sendUnsentMessages(AdapterOutboundProcessor.java:221)
	at xi.adapter.outbound.scheduler.OutboundMessageScheduler.run(OutboundMessageScheduler.java:66)
Caused by: com.sap.engine.services.ejb.exceptions.BaseRuntimeException: Cannot create an instance of the stateless bean.
	at com.sap.engine.services.ejb.session.stateless_sp5.BeanFactory.getActiveBean(BeanFactory.java:192)
	at com.sap.engine.services.ejb.session.stateless_sp5.StatelessContainerFP.getActiveBean(StatelessContainerFP.java:183)
	at xi.adapter.messageDB.MessageServiceLocalLocalObjectImpl40.getUnsentMessages(MessageServiceLocalLocalObjectImpl40.java:1146)
	... 2 more
Caused by: com.sap.engine.services.connector.exceptions.BaseRuntimeException: Resource system and application components cannot be used in system threads.
	at com.sap.engine.services.connector.jca.ResourceSetContextObject.popRecord(ResourceSetContextObject.java:101)
	at com.sap.engine.services.connector.resource.impl.ResourceContextImpl.exitMethod(ResourceContextImpl.java:154)
	at com.sap.engine.services.ejb.session.stateless_sp5.BeanFactory.createObject(BeanFactory.java:141)
	at com.sap.engine.services.ejb.util.pool.ContainerPoolImpl.doResizeOneStepUp(ContainerPoolImpl.java:374)
	at com.sap.engine.services.ejb.util.pool.ContainerPoolImpl.ensureNotEmpty(ContainerPoolImpl.java:343)
	at com.sap.engine.services.ejb.util.pool.ContainerPoolImpl.pop(ContainerPoolImpl.java:291)
	at com.sap.engine.services.ejb.session.stateless_sp5.BeanFactory.getActiveBean(BeanFactory.java:188)
	... 4 more

Does anybody has an idea about this behavior. Help is - as always - highly appreciated and will be rewarded.

Thank you in advance!!!

Kind regards,

Matthias